The primary package referred to as Pool is [Pool (Kupries)].
However, see also

 What: Pool (Leunissen)
 Where: See contact
 Description: Tcl only package for managing pools of discreate items.
 Updated: 06/2002
 Contact: <URL: mailto: e dot leunissen at hccnet dot nl >

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I think this is the same package, as the tcllib struct::pool package.
http://tcllib.sourceforge.net/doc/pool.html

Yes, Eric submitted this to tcllib, and it was included.

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[Category Package]